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Re: [libvirt] [PATCH 0/6] auto-assign addresses when <address type='pci'/> is specified



On 05/20/2016 02:32 AM, Ján Tomko wrote:
On Thu, May 19, 2016 at 05:14:33PM -0400, Laine Stump wrote:
On 05/19/2016 01:23 PM, Ján Tomko wrote:
Yes, qemu_hotplug.c has a few of those places using == DEVICE_ADDRESS_TYPE_PCI
untouched by this series.
Since they happen after parse is finished, it should be safe.

And anyway, looking at those uses, I think what most of them are doing
(calling virDomainPCIAddressEnsureAddr()) is 100% unnecessary, since
it's now already done when addresses are assigned in
qemuDomainDefAssignAddresses(), which has already been called.
Actually, virDomainPCIAddressEnsureAddr is the place where the address
gets assigned.

Exactly. But I was looking only at the _CONFIG version of hotplug, and saw that the PCI address had already been assigned by the time we called EnsureAddr, so it was superfluous. I didn't catch the bit that you point out below - in the case of live-only that assignment isn't done.

  But only when address == NONE or PCI, which is OK because
virDomainPCIAddressEnsureAddr calls PCIAddressIsPresent to decide
whether it needs to allocate a new one.

qemuDomainDefAssignAddresses is only called after parsing the whole
domain, not just one device.

Cole pushed a patch yesterday to cause it to be called during attach-device as well, but only in the case of _CONFIG, so your point still stands. I guess the patch to remove the other EnsureAddr stuff needs to be combined with moving that AssignAddresses call to a point that is common for live and config (which makes sense - they really do both need the same address)


(Back in
Jan 2010 when the calls to qemuDomainPCIAddressEnsureAddr() were added
(commit d8acc4), this was not the case - they were needed in order for
the new devices to get an address assigned, but a lot has changed since
then - even before Cole put in the postparse callback address assignment
stuff and called it when attaching a device, we had already been
assigning addresses during the higher level qemuDomainAttachDeviceConfig
for a long time (since commit f5dd58a in June 2012;
qemuDomainAttachDeviceConfig is for changing the persistent definition.
Hotplug in qemuDomainAttachDeviceLive does not call any other address
assignment function.

Yeah, I missed that in my haste.


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